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Dynamical symmetries in Brans-Dicke cosmology
(American Physical SocietyPhysical Review D, 2017-01-20)
In the context of generalized Brans-Dicke cosmology we use the Killing tensors of the minisuperspace in order to determine the unspecified potential of a scalar-tensor gravity theory. Specifically, based on the existence ...
Probing the Gravitational Dependence of the Fine-Structure Constant from Observations of White Dwarf Stars
(Multidisciplinary Digital Publishing InstituteUniverse, 2017-06-01)
Hot white dwarf stars are the ideal probe for a relationship between the fine-structure constant and strong gravitational fields, providing us with an opportunity for a direct observational test. We study a sample of hot ...
Kinematics of Einstein-Cartan universes
(American Physical SocietyPhysical Review D - Particles, Fields, Gravitation and Cosmology, 2017-05-08)
We analyze the kinematics of cosmological spacetimes with nonzero torsion, in the framework of the classical Einstein-Cartan gravity. After a brief introduction to the basic features of spaces with nonvanishing torsion, ...
Evolution of cyclic mixmaster universes with noncomoving radiation
(American Physical SocietyPhysical Review D, 2017-12-15)
We study a model of a cyclic, spatially homogeneous, anisotropic mixmaster universe of Bianchi type IX 'mixmaster' universe, containing the a radiation field with non-comoving ('tilted' with respect to the tetrad frame of ...
Cosmological models in energy-momentum-squared gravity
(American Physical SocietyPhysical Review D, 2017-12-15)
We study the cosmological effects of adding terms of higher-order in the usual energy-momentum tensor to the matter lagrangian of general relativity. This is in contrast to most studies of higher-order gravity which focus ...
Maximum magnetic moment to angular momentum conjecture
(American Physical SocietyPhysical Review D, 2017-03-24)
Conjectures play a central role in theoretical physics, especially those that assert an upper bound to some dimensionless ratio of physical quantities. In this paper we introduce a new such conjecture bounding the ratio ...
Cyclic mixmaster universes
(American Physical SocietyPhysical Review D, 2017-04-19)
We investigate the behavior of bouncing Bianchi type IX “mixmaster” universes in general relativity. This generalizes all previous studies of the cyclic behavior of closed spatially homogeneous universes with and without ...
Cosmological solutions with gravitational particle production and nonzero curvature
(American Physical SocietyPhysical Review D - Particles, Fields, Gravitation and Cosmology, 2017-05-26)
In a homogeneous and isotropic universe with nonzero spatial curvature we consider the effects of gravitational particle production in the dynamics of the universe. We show that the dynamics of the universe in such a ...